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CONTROL SYSTEM 5 Sheets-Sheet 1 Filed May 6, 1963 S R v! o M m EEC W W A H 5 S I LT m WM 5 V HEY B Eoninm 29233;? 52 5:

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CONTROL SYSTEM 3 Sheets-Sheet 2 Filed May 6, 1963 A TRANSLATED p SIGHT LINE PROTRACTED SIGHT .1- LINE SUPPORT REFERENCE (FIXED GuNI TARGET 1 AT OPTICAL INFINITY CORRECTION I PICK-OFF SIGHT LINE SUPPORT TARGET *2 AT OPTICAL INFINITY PROTRACTED SIGHT LINE SUPPORT WE I V! m m 5 Ru 0 L RC T T K v R R NOC w N 5 0 I AIWS IA S N H T m 5 A T L T M T AM I C mTz R Iv N 5 A& 0 I E G T W U E 1%..V #WIG M E Hm Y HF ELT.\ N E G w II E Qmm CI E0 A IQII\ .V-I. ALUT m I i e m r\ V I Z S u T m T E G1 R8 A T y 1966 H. SHAPIRO ETAL 3,262,210

CONTROL SYSTEM 5 Sheets-Sheet 5 Filed May 6, 1963 PHASE DETECTOR DEVICE A 2 CONTROL FIG. 7.

SUMMING CIRCUIT INVENTORS HENRY L. SHAP/RO EVERETT T. SHOCKLE) ATTORNEY United States Patent 3,262,210 CONTROL SYSTEM Henry L. Shapiro, Massapequa, and Everett T. Shockley,

Williston Park, N.Y., assignors to Sperry Rand Corporation, Great Neck, N.Y., a corporation of Delaware Filed May 6, 1963, Ser. No. 278,313 6 Claims. (CI. 3346) This invention relates in general to apparatus for use in controlling other apparatus and in particular provides apparatus that controls other apparatus in accordance with head movements of an operator.

To emphasize the significance of the invention, the specification describes use of the invention in control of the aiming of a weapon system, for here accuracy of control is most critical. Specifically, use as herein described is made of the invention to direct weapons from a helicopter, such direction being dependent upon the line of sight of the helicopter operator.

Generally, the invention provides head gear having a built-in sight with reticle, the connections of such head gear to the craft having signal producing pick-offs thereon which produce signals useful in directing the Weapons of the helicopter. The provided head gear, while being worn by a helicopter pilot, permits such pilot to move freely about and Within his cockpit, and in addition permits the pilot to aim his weapons from substantially any cockpit location. Hence, the pilot need only look at a target to determine whether to shoot or not: If the determination is to shoot, the pilot depending on whether his weapons are adapted to follow his head movements or whether they are fixedly supported by the helicopter, respectively pulls his trigger, or first guides his craft to align his guns in the direction that he is looking and then pulls his trigger.

Admittedly, prior art apparatus have provided for elevational and azimuthal directing of weapons in accordance with the head motion of the wearer of head-supported sighting apparatus. See for example US. Patent 3,051,047. Such apparatus provides indications of the tip-down and right-left head motions of an operator, and requires that the head of the operator be positionably confined (i.e. fixed with respect to a given line of sight). With the present invention translational motion of the operator is not only possible, but is inherently corrected for by the apparatus itself. That is, with the instant invention the pilot of a helicopter may slide around in his seat, bend forward etc. to look at a traget, and then decide whether to shoot or not as described above.

Aside from providing full articulation of head-supported sighting apparatus, the present invention further sets forth a novel system control technique that facilitates use of fixed weapons. That is, by use of four tiny lamps visible to, but so located as to be substantially within the normal minimum focal distance of, the eye of the pilot (Le. less than approximately ten inches), thereby requiring that the pilot look past such lights to see his targets, the pilot may effect horizontal and vertical control of the craft in accordance with the manner in which the lamps are lighted. This will be described in detail later.

A principal object of the invention is to provide sighting apparatus for use in the control of other apparatus.

Another object of the invention is to provide sighting apparatus that is adapted to be worn on the head of a person in control of other apparatus, and which apparatus effects such control according to a line of sight pro vided by the sighting apparatus.

Another object of the invention is to provide sighting apparatus adapted to be worn on the head of an operator of, for example, an aircraft, such apparatus allowing relatively free movement of the operator adjacent his 3,262,210 Patented July 26, 1966 ice control station and providing signals representative of the angular displacements of the head of such operator with respect to a reference direction fixed in the craft.

Another object of the invention is to provide a control indicator that uses four lamps substantially orthogonally displaced with respect to each other, said lamps being all radially disposed about a line of sight.

Another object of the invention is to provide a control indicator that utilizes four lamps orthogonally displaced with respect to each other in the field of view of an operator, the lamps being positioned so close as to be within the normal mini-mum focal distance of the eye of the operator.

The invention will be described with reference to the figures wherein:

'FIG. 1 is a block diagram showing the general arrangement of components in a presently preferred form of the invention,

FIG. 2 shows a support and pick-off device for producing signals representing angular displacements of the head of an operator with respect to a reference direction, such device permitting substantially free translational and rotational head motions,

FIG. 3 is a perspective view showing how the apparatus of FIG. 2 may be connected to suitable head gear such as a helmet,

FIGS. 46 are diagrams useful in describing how the apparatus of FIG. 2 operates,

FIG. 7 is a block diagram showing a presently preferred form of circuit adapted to use signals provided by the apparatus of FIG. 2,

FIG. 8 is a perspective view of a presently preferred form of head gear employing the invention, and

FIG. 9 is a schematic diagram of a circuit useful in controlling the control indicator of FIG. 8.

Referring to -FIG. 1, a sight or reticle secured to a helmet 12 worn by, for example, the pilot of an aircraft, such as a helicopter, defines a line of sight for the pilot that is fixed relative to the helmet, that is, relative to a support bracket secured to the helmet. The helmet 12 connects to an articulation support 14 between the helmet bracket and a fixed reference direction or a reference point in helicopter, which support permits substantial rotational and translational motion of the helmet 12 relative to the craft while it is being worn, i.e. the helmet articulation support 14 itself does not unduly restrict substantial head motion. Signal pick-offs 16 (normal and corrector) are connected to the helmet 12 to produce (1) signals l/ and 6 representing angular displacements of the head in mutually perpendicular planes, for example, in azimuth b) and elevation (0) relative to the fixed craft reference direction, and (2) correction signals w and 6 for use in cancelling the adverse effects of translational movements of the head in these planes with respect to the reference direction. As will be described later, the normal and corrector pick-offs *16 in the presently preferred embodiment of the invention are identical in form, e.g. both are synchros or both are potentiometers. The signals from the pick-offs 16 are applied to a conventional fire control computer and control device 18 which produces resultant control signals for directing weapons and the like in azimuth and elevation relative to the craft according to the direction of the line of sight defined by the sight 10.

Referring now to FIG. 2 the support 14 and pick-oifs 16 of FIG. 1 are combined into a single unit or coupling means between the helmet 12 and a reference support fixed angularly relative to the helicopter fore and aft axes. A T-shaped member 20 having a shaft 22 is adapted to be rigidly secured as shown in FIG. 3 in a bracket 24 which in turn is rigidly secured to the back of the helmet 12. The shaft 22 is free to rotate about its own axis relative to a bearing support 26, thereby providing a swivel connection for the helmet 12 to permit relative freedom of movement of the pilots head about the sight line. The bearing support 26 is rigidly secured to the shaft 30 to rotate the rotor of a pick-01f 32, e.g., a synchro or potentiometer, such pick-off shaft 30 being free to rotate generally in elevation with respect to a supporting block 41 which supports the stator 34 of the pick-off 32. The block 41 is free to rotate about an azimuthal axis of yoke 28, see the schematic diagram of FIG. 4, the axis designated X-X. The stator 36 of a second pick-off 38 is rigidly secured to the gimbal or yoke 28, the rotor thereof being rigidly secured to block 41. Therefore, by preventing rotation of gimbal 28 about the reference direction, the shaft 30 of the elevation pick-off 32 will always rotate about a horizontal axis and the shaft 40 of the pick-off 38 will always rotate about a vertical axis. Thus, elements 28 and 41 constitute a universal joint having an azimuth pick-off 38 and an elevation pick-off 32 which generate signals proportional respectively to the azimuth and elevation angular movements of the helmet relative to a coupling shaft 42.

The universal connection 28, 41 is mounted at the helmet end of the shaft 42 which in the embodiment illustrated consists of a protractible rod 44 slidably movable within a cylindrical support 46. The rod 44 has spaced apart braces 48 which connect to an anti-roll bar 50, such anti-roll bar being slidably movable within a brace 52 secured to the cylindrical support 46. Therefore, the rod 44 is prevented from rotating about its own axis, relative to cylinder 46, the latter in turn being non-rotatable in roll relative to the craft as described below, with the result that the gimbal 28 is prevented from rotating in roll, and the shafts 30 and 40 are therefore restrained to rotate only about an axis parallel to the craft pitch and yaw axes respectively, i.e. about elevation and azimuth axes.

A pair of pick-offs 60 and 58, like the pick-offs 32 and 38, are supported by a yoke 54. The rotor shaft 56 of a craft azimuth pick-off 58 rigidly connected to the cylindrical support 46, is mounted in a block 61 for rotational freedom about -a normally vertical axis parallel to the craft yaw or azimuth axes, the stator of the pick-off 58 being carried by the block 61. The block 61 is pivotally mounted between the arms of yoke 54 for angular freedom about an elevation axis parallel to the craft pitch axis. A craft elevation pick-off 60 has its stator secured to one arm of yoke 54, with the rotor thereof being connected rigidly to block 61. Thus, the elements 5661 constitute a second universal joint having an azimuth shaft pick-off 58 and an elevation shaft pick-off 60 which generate signals respectively proportional to the azimuth and the elevational angular movements of the shaft 42 relative to the fore and aft axes of the helicopter which,

in the present case, constitutes the reference direction.

That is, the reference direction is defined by the support 64 which is secured to the helicopter structure preferably directly behind the pilots head and provides the reference support with respect to which the reference direction is fixed.

It should be noted at this point that the helmet 12 is so constructed and arranged as to fit the pilots head so that it follows all angular movements of his head in azimuth and elevation. Therefore, with the sight line defining means 10 rigidly fixed with respect to the helmet 12 and in line with the normal straight ahead position of the eyeball within its socket, the pilot, in observing a target through the sight 10, will naturally move the helmet so that, in effect, it is likewise substantially aligned with the line of sight. Thus, the shaft 22 which is rigidly connected to the helmet through bracket 24 itself repeats the direction of the line of sight of the operator.

To understand how the apparatus of FIG. 2, in conjunction with a helmet worn by a helicopter pilot, may provide signals representative of the elevation and azimuth that the line of sight of the wearer of such helmet is with relation to a reference direction fixed relative to the craft, reference should be had first to FIG. 5. Shown is a reference direction, which may for example be a direction corresponding to the fore and aft axis of a helicopter and in most cases the direction that fixed helicopter guns or missile launchers are aimed. The line of sight defined by the optical sight 10' (for the situation where the pilot of the helicopter is boresighted with respect to the craft fore and aft axis), makes an azimuthal angle 1// =0 with respect to the craft fore and aft axis and hence with the reference direction when the pilot looks at a first target (Target #1) directly ahead in azimuth and which in most cases is at optical infinity. In order to look at a second target through the sight, the pilot rotates his head thereby rotating the sight line in azimuth with respect to the reference direction through an angle b 0. In the schematic diagram of FIG. 5, the azimuthal pick-off AZ.P.O., located first at position P provides a signal proportional to azimuthal changes in the direction of the line of sight from Target #1 to Target #2 directly, i.e., at position P the pick-off AZ.P.O. produces a signal representing the angle Should the pilot for some reason change his position laterally within the cockpit, say, from 'P to P, and then look at the aforementioned two targets, the articulated support of FIG. 2 operates to provide the same azimuthal i/l as follows: In changing position within the cockpit, the protractible shaft 42 being anchored to the pi-lots helmet extends, i.e., the rod 44 will slide within its cylindrical support 46. The shaft 42 therefore rotates shaft 56 through an angle b In maintaining the sight line on Target #1 the pilot naturally counterrotates his head through the same angle lll this being true since Target #1 appears at optical infinity. If the pilot, at position P, looks at Target #2, the angle measured by AZ.P.O. will increase by the amount i i.e. l/ =1// In other words, the pick-off AZ.P.O. (38) produces always the signal b which is the algebraic sum of angles ti/ produced by correction pick-off 58 and h produced by azimuth pick-off 38. In this way, the true azimuthal error signal 1,0,, relative to the reference direction always results through the correction or shaft pick-off 58. This computation may be accomplished simply by serially connecting the pick-offs 38 and 58 or the signals may be taken separately and supplied to the computer and control device 18 as shown in FIG. 1.

The above description is presented to show how the support 14 may provide true azimuthal control signals regardless of how the pilot laterally translates his location within his cockpit. It will be understood that the generation of elevation signals is identical with the generation of azimuth signals and duplication of the above description for elevation is deemed necessary.

As stated above, the sight line support 14 in the illustrated embodiment connects to the back of the helmet 12 which is so Constructed and arranged as to follow the movements of the pilots head. Were it not for the present invention, this would prevent proper operation of the sighting apparatus, because the azimuthal signal 1/1 desired must represent an angular displacement in azimuth and elevation of the line of sight of the eye about its own axis (assuming the eyeball is fixed in its socket which will be the case since the line of sight is defined by the helmet-mounted sight 10), and not about an axis of rotation at the rear of the head of the helicopter pilot. To see how the instant invention allows for a displaced axis of rotation, i.e. the distance between the pivot support 2841 and the eyeball, while producing an azimuthal signal (the problems in elevation being the same as in azimuth), reference should be had to FIG. 6. In FIG. 6, the sighting eye #1 remains translationally fixed, but rotationally movable; that is, the pilots head remains at position P in FIG. 5 and merely rotates in azimuth. Turning of the sight 10 and hence the line of sight counterclockwise through the angle 0,, from Target #1 to Target 5 #2 the whole pick-off AZ.P.O. (38) likewise rotates in location through this same angle about the vertical axis of eye #1 which causes the shaft 42 to extend and rotate about the axis of the shaft 56 throughthe angle 1,0

At the same time azimuth shaft pick-off 38 is likewise rotated through the angle 0 which, as above, equals il/ +ip By inspection, it can be seen that the shaft 40 of the pick-off AZ.P.O. (38) must rot-ate through the angle rl/ i.e. b -H1 when the sighting eye #1 secs Target #2. Now by algebraically adding (as above) th signal \l/ produced by the correction pick-off (58) to the signal L the signal b may be produced.

Thus the operation of the system for angular movements only of the head in azimuth, for systems where the shaft 42 is coupled at the back of the helmet, is identical to that for translational movements of the head relative to the craft reference support 64.

Referring to FIG. 7, apparatus for algebraically adding 0; and b has the normal azimuthal signal ip i.e., the signal representative of the actual amount that the azimuth pick-off shaft 40 rotates through, applied to a summing circuit 68. The signal 1p provided by the shaft azimuth pick-off 58, is ordinarily of a phase opposite to the phase of the signal gl/ provided by the pick-off 38, and is applied also to the summing circuit 68. The summing circuit 68 algebraically adds its input signals and provides therefore an output signal proportional to, in all cases, only the signal h A phas detector 70, receiving a reference signal of a known phase, compares such phase with the phase of the output signal from the summing circuit 68 and produces a D0. signal having a polarity dependent upon the phase of the signal b i.e. the phase of the signal 11 indicates the direction that the sight line is rotated with respect to the reference direction. A control device 72 then receives the polarized output signal from the phase detector 70 to provide an indication to the pilot (or if preferred a control signal to a servo which drives positionable guns etc.) of the direction that he needs to control his craft to align his guns, i.e. his reference direction, with his sight line. Identical circuit components are provided for elevation control, being shown generally by a block 74.

In its presently preferred form, the control device 72 is connected to control suitable indicating means coupled with the helmet 12 as shown in FIG. 8. Shown in FIG. 8 is a helmet 12' having a sight e.-g. the sight shown and described in US. Patent 2,420,252. The sight It) is adapted to be fixedly positioned on a transparent supporting visor 76 so that the pilot can look around the sight or through the sight as the case may be. Positioned respectively above and below the sight 10' are two small lamps U and D, e.g. so-called Grain-of-Wheat bulbs, which are controlled in accordance with the polarity of the output signal from the phase detector in the circuit block 74. Positioned to the left and right of the sight are two lamps L and R (like the lamps U and D) which are controlled in accordance with the sense or polarity of the output signal from the circuit 70. When the line of sight defined by the sight 10' is directed in the reference direction, assuming fixed guns or missiles boresighted with the helicopter fore and aft axis, all lamps U, D, L and R light. When the pilot turns his head rightward to select a new target for example, the right light goes out, indicating to him that he must maneuver his craft around to align the guns with the sight line. Updown control of the craft is similar to left-right control. (The lamps U, D, L and R may, if preferred, be adapted to remain normally out, and be lit only when the aircraft is not properly oriented relative to the sight line.

The same teachings apply, of course, as intimated above to guns or missile launchers which are movably mounted on the helicopter or other vehicle. In this case the weapons are positioned as to be maintained substantially in line with the line of sight, assuming, of course, the inclusion of the usual ballistics correction angles, etc.

For a circuit for selectively controlling the lamps U, D, L and R, reference should be had to FIG. 9 which shows the lamps excitable through switching circuits 78 and 80, such circuits operating selectively to turn normally lit lamps off when the head of the pilot turns in a direction different from the reference direction. The azirnuth switching circuit 78, which is identical to the elevation switching circuit 80, has a dead zone circuit 79 (e.g. like the circuit of Fig. 6.23c shown on page 292 of Electronic Analog Computers, Korn and Korn, McGraw- Hill Book Company, New York) the input signal to which is applied in parallel to biased diodes 82 and 84. The diode 82 is biased in reverse to pass positive signals above a certain threshold, and the diode 84 is similarly biased in reverse for negative signals; the diodes 82 and 84 are respectively connected to operate relays 86 and and 88, which in turn respectively open normally closed switches 90 and 92. The switch 90 on opening removes power from the lamp R; the switch 92 on opening removes power from the lamp L.

So long as the signal \l/ on contact A at the output of the phase detector 70 falls within the dead zone of the circuit 79 (or as the case may be, the elevation signal 0 at contact B), no output signal gets applied to the relays 86 and 88, with the result being that both lamps L and R remain lit. Once the pilot moves his head, say to the right, the phase detector 70 produces a positive signal which, depending on the adjustable bias provided by the batteries in the dead zone device 79, causes the relay 86 to energize and open the switch 90, thereby causing the lamp R to go out. Similarly, the other lamps are made to go out by leftward, upward and downward motion of the head of the pilot. Note should be made that the resolution afforded by the helmet sight is deliberately made adjustable by means of the dead zone batteries so that, depending on how steady the pilot can hold his head still, hell be able to keep the lights U, D, L and R lit.

While the invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in its broader aspects.

What is claimed is:

1. In a sighting appaartus for use in producing control signals representative of the angular displacements of the sight line of an operator about orthogonal axes relative to a fixed reference direction normal to said orthogonal axes, the combination comprising (a) a reference support member with respect to which the reference direction is fixed,

(b) head gear including line of sight defining means adapted to be worn by said operator and including a further support member that is fixed relative to the head of the operator,

(c) coupling means between said reference support member and said head gear support member for generating said control signals while permitting free translational movement therebetween, said coupling means comprising (1) shaft means extending between said reference support member and said head gear support member,

(2) first means pivotally connecting one end of said shaft means to said reference support member for freedom about said orthogonal axes,

(3) second means pivotally connecting the other end of said shaft means to said head gear support member for freedom about said orthogonal axes,

(4) first and second pick-off means at each of said pivot connections and responsive to angular movements of said shaft means about each of said orthogonal axes, and

(5) means for algebraically combining the signals produced by each of said pick-off means for producing resultant control signals proportional to angular movements only of said line of sight relative to said fixed direction.

2. The combination as set forth in claim 1 further including means connected with said support members for preventing rotation of said shaft means about an axis parallel to said reference direction.

3. The combination as set forth in claim 1 wherein said pivotal connections comprise universal joints providing angular movements of said head gear support about said orthogonal axes and said first and second pick-off means are mounted on the respective axes of said universal joints.

4. The combination as set forth in claim 3 wherein each of said first and second pick-off means comprises a first signal producing means connected to one axis of the universal joint coupling said shaft to said head gear support member for providing a signal corresponding to angular movement of said sight line relative to said shaft about said one axis and a second signal producing means connected to a corresponding axis of the universal joint coupling said shaft to said reference support for providing a signal corresponding to angular movements of said shaft relative to said reference direction, and means algebraically combining said signals for providing an output signal proportional only to angular movements of said line of sight relative to said reference direction.

5. The apparatus of claim 1 including director lamps radially disposed relative to said sight line in directions corresponding to said orthogonal axes and in the vertical field of view of the operator, and means for controlling said lamps at least in accordance with the sense of said resultant control signals whereby visually to indicate to the operator the sense of movement of said sight line relative to said reference direction.

6. Sighting apparatus for use by an operator in controlling a device having a reference axis and adapted to be moved in dependence upon the movement of the sight line of the operator, the combination comprising (a) head gear adapted to be worn by the operator and to follow the up-down, right-left angular movements of the operators head and including support means fixed thereto,

(b) sight means secured to said head gear and so positioned relative to the operators line of vision as to define the line of sight of the operator,

(c) support means carried by the device for defining the reference axis thereof,

(d) coupling means between said head gear support and said reference axis defining support means for generating control signals proportional to the updown, right-left angular movements of the operators head relative to said reference axis,

(e) indicator means carried by said head gear and disposed adjacent to said sight line defining means and adapted to provide up-down and right-left indications to the operator, and

(f) means for controlling said indicator means in accordance with said respective control signals whereby to provide the operator with an indication of the movement of said sight line relative to said reference axis.

References Cited by the Examiner UNITED STATES PATENTS 1,605,725 11/ 1926 Herbert. 2,757,574 8/1956 Thorburn 88-36 X 2,848,924 8/1958 Potez 88-36 3,051,047 8/1962 Fieux 88-36 3,070,886 1/1963 Tassie 33-47 3,124,329 3/1964 Ransom et a1 88-36 X 3,161,846 12/1964 Wagner et al.

FOREIGN PATENTS 931,321 7/1963 Great Britain.

40 ROBERT B. HULL, Primary Examiner. 

1. IN A SIGHTING APPARATUS FOR USE IN PRODUCING CONTROL SIGNALS REPRESENTATIVE OF THE ANGULAR DISPLACEMENTS OF THE SIGHT LINE OF AN OPERATOR ABOUT ORTHOGONAL AXES RELATIVE TO A FIXED REFERENCE DIRECTION NORMAL TO SAID ORTHOGONAL AXES, THE COMBINATION COMPRISING (A) A REFERENCE SUPPORT MEMBER WITH RESPECT TO WHICH THE REFERENCE DIRECTION IS FIXED, (B) HEAD GEAR INCLUDING LINE OF SIGHT DEFINING MEANS ADAPTED TO BE WORN BY SAID OPERATOR AND INCLUDING A FURTHER SUPPORT MEMBER THAT IS FIXED RELATIVE TO THE HEAD OF THE OPERATOR, (C) COUPLING MEANS BETWEEN SAID REFERENCE SUPPORT MEMBER AND SAID HEAD GEAR SUPPORT MEMBER FOR GENERATING SAID CONTROL SIGNALS WHILE PERMITTING FREE TRANSLATIONAL MOVEMET THEREBETWEEN, SAID COUPLING MEANS COMPRISING (1) SHAFT MEANS EXTENDING BETWEEN SAID REFERENCE SUPPORT MEMBER AND SAID HEAD GEAR SUPPORT MEMBER, (2) FIRST MEANS PIVOTALLY CONNECTING ONE END OF SAID SHAFT MEANS TO SAID REFERENCE SUPPORT MEMBER FOR FREEDOM ABOUT SAID ORTHOGONAL AXES, 